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D6507-19 – Standard Test Method Technical Guide
ASTM D6507‑19 establishes a standardized practice for creating fiber reinforcement orientation codes for continuous‑fiber‑reinforced composite materials. This practice provides a consistent methodology for describing laminate and braid lay‑ups, drawing on established industry practices and leading composite material handbooks. The standard was developed in accordance with internationally recognized principles on standardization issued by the WTO TBT Committee.
📜 Scope and Significance of the Orientation Code
The primary purpose of the laminate orientation code defined in this standard is to provide a simple, easily understood method for describing the lay‑up of a laminate. The code is largely based on industry practice, the NASA/DOD Advanced Composites Design Guide, CMH‑17‑2G, and ISO 1268‑1. While explicitly provided for two‑dimensional laminates and braids, the laminate code may also be used for filament‑wound materials.
📋 Practical Application: The laminate code defined in this standard can be applied to filament‑wound materials, providing a unified orientation system across different manufacturing processes such as laminating, braiding, and winding.
🗺️ Establishing the Reference Systems
Before writing the orientation code, a set of reference coordinate axes must be selected. The reference plane is selected as either the bottom or top layer of the laminate. For a laminate symmetric about its midplane, the orientation code using the top layer as the reference plane is identical to the orientation code using the bottom layer as the reference plane.
The reference direction, from which ply orientation is measured, is selected for convenience and relevance to the application. Often, a dominant fiber direction, such as that aligned with the laminate principal axis, is defined to be 0°. An example of this is the Test Method D3518/D3518M for in‑plane shear response of a ±45° laminate.
| 🟦 Document / Standard | 📏 Description and Role |
|---|---|
| ASTM D3518/D3518M | Test Method for In‑Plane Shear Response; demonstrates setting the reference direction to 0° along the test axis for a ±45° laminate. |
| ASTM D3878 | Provides standard terminology for composite materials used throughout this practice. |
| CMH‑17‑2G | Polymer Matrix Composites, Volume 2; foundational source for the laminate stacking designation system. |
| ISO 1268‑1 | Fibre‑reinforced Plastics – Methods of Producing Test Plates; provides international stacking designation systems. |
⚙️ Codes for Laminates and Braids
The practice establishes distinct orientation codes for two‑dimensional laminates and braids. The braiding code is based largely on the Standard Test Methods for Textile Composites. For computerized formats that do not permit subscript notation, the standard includes a specific method for presenting this subscript information. The standard emphasizes that terminology in accordance with ASTM D3878 must be used where applicable.
| 📐 Component | 🎯 Specification |
|---|---|
| Reference Plane | Selected as the bottom or top layer. The code progresses through the laminate thickness from this selected plane. |
| Reference Direction | Arbitrary, but often aligned with a dominant fiber direction (e.g., the laminate principal axis defined as 0°). |
| Applicable Materials | Continuous‑fiber‑reinforced composite materials, including 2D laminates, 2D braids, and filament‑wound structures. |
| Symmetric Laminates | The code is identical whether the top or bottom layer is used as the reference plane. |
⚠️ User Responsibility: This standard does not purport to address all safety concerns. It is the responsibility of the user to establish appropriate safety, health, and environmental practices prior to use.
❓ Frequently Asked Questions
🔍 Does D6507‑19 apply to both laminates and braids?
Yes. Orientation codes are explicitly provided for two‑dimensional laminates and two‑dimensional braids. Additionally, the laminate code may be used for filament‑wound materials, broadening its scope of application.
⚡ How is the 0° fiber direction determined according to this practice?
The reference direction is selected for convenience and relevance to the application. Often, a dominant fiber direction, such as that aligned with the laminate principal axis, is defined to be 0°.
📌 How is subscript information handled in computer systems?
A specific method is included in the standard for presenting subscript information in computerized formats that do not permit subscript notation, ensuring the code can be accurately entered into databases.
💡 Does the choice of reference plane change the orientation code?
For a laminate symmetric about its midplane, the orientation code using the top layer as the reference plane is identical to the orientation code using the bottom layer as the reference plane.